1. Field of the Invention
This invention relates to a decolorizable dye. More specifically, the present invention pertains to a decolorzable dye which becomes colorless rightly after solution treatment.
2. Description of the Related Art
Enormous efforts have been made for decreasing color remaining (residual color) which occurs after processing of a silver halide photographic material. Particularly in recent years, with a view to satisfying environmental countermeasures and user's needs, there has been a strong demand for processing speed enhancement and replenishment reduction of a photographic processing solution. A sensitizing dye or pigment (which will hereinafter be called "photographic dye" collectively) therefore needs a new molecular design utterly different from that of the conventional one.
It is widely known that color remaining of a photographic dye is effectively reduced by washing away the dye, which has hydrophilic property enhanced, into a processing solution upon photographic processing. The enhancement of hydrophilic property however usually impairs the adsorption property of a sensitizing dye to silver halide grains and adversely affects the performances of photograph such as sensitivity, fog and storage stability. It is therefore very difficult to attain reduction in color remaining and other photographic performances at the same time.
Investigations have been energetically carried out in order to remove the color of a photographic dye by making use of the chemical reaction between the dye and an additive of a photographic processing solution such as nucleophilic agent, electrophilic agent, oxidizing agent or reducing agent, or other chemical species. There are however not so many additives which do not worsen the photographic performances and complete suppression of color remaining by the reaction with a dye has been found to be difficult as a result of investigations so far made.